Androgen receptor gene mutations in human prostate cancer.

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Abstract
We screened human prostate cancer tissues for the presence of somatic mutations in the hormone binding domain of the androgen receptor (AR) gene. Exons E-H were amplified from genomic DNA using the polymerase chain reaction and analyzed by denaturing gradient gel electrophoresis (DGGE), which separates DNA fragments that differ by only a single base. We detected a mutation in exon E of the hormone binding domain in 1 of 26 specimens of untreated organ-confined stage B prostate cancer. The mutation was not detectable in peripheral blood lymphocyte DNA. Lymphocyte DNA (wild-type AR) migrated in DGGE as a single band. The tumor DNA migrated in DGGE as four bands, consistent with the presence of cells with mutant AR plus cells with wild-type AR and indicating that the tumor contained a somatic mutation. To our knowledge, a somatic AR gene mutation has not been reported previously. Sequencing revealed a G----A substitution in codon 730, changing valine to methionine. Codon 730 is in a region highly conserved among all steroid receptors. The abundance of the mutated fragment (about 50% of the DNA in the specimen) indicates its presence in cells with a growth advantage. A somatic mutation could be detected by DGGE if it represented at least 10% of the sample. Failure to detect mutations in other specimens analyzed may be due to this limit of sensitivity, the presence of mutations in other parts of the AR, or a low frequency of mutations in early stage disease.